Process and apparatus for retorting of oil shale



May 5, 1959 L P- EVANS 2,885,338

n PROCESS AND APPARATUS FOR RETORTING oF OIL SHALE Filed Dec. 4, 1953 ssheefs-sheet 1 c'afvDf/vsw HND HE/IT EKCHNE ZONE MIX/N6 ZONE May 5, P.EVAN$ PROCESS AND' APPARATUS FOR RETORTING OF OIL SHALE Filed Dec. 4,1953 3 Sheets-Sheet 2 May 5, 1959 L .,P. EVANS 2,885,333

APROCESS AND APPARATUS FOR RETORTING OF' OIL SHAL Filed Dec. 4, 1953 3Sheets-Sheet 3 Y [amis j? fz/m15 B United States Patent PROCESS ANDAPPARATUS FOR RETORTING F OIL SHALE Louis P. Evans, Woodbury, NJ.,assignor to Socony Mobil Oil Company, Inc., a corporation of New YorkApplication December 4, 1953, Serial No. 396,221

Claims. (Cl. 208-11) This invention relates to an improved method andapparatus for recovering valuable hydrocarbons from hydrocarbonaceoussolids such as oil shales, coal, peat, lignite, tar sands and the like.It is more particularly concerned with an improved apparatus and processwherein a hydrocarbonaceous solid is retorted economically andefficiently, with a substantially complete recovery of heat and withinternal fractionation of the liquid and gaseous products.

As is well known to those skilled in the art, normally l liquid andgaseous hydrocarbons have been recovered from hydrocarbonaceous solidsby means of processes which include heating or roasting the solids atelevated temperatures suliicient to educt the desired hydrocarbons andto separate them from residual mineral matter. Commercial retortingoperations which have been ernployed hereinbefore have been cumbersome,expensive and unsatisfactory for large scale operations. For example,commercial shale retorting methods have required enormous equipmentinstallations with proportionately small recovery of shale oil. Themethods have generally involved the use of vertical cast iron retortsthrough which lumps of shale pass by gravity, heat has ordinarily beensupplied through the retort walls. In other methods rotary kiln retortshave been used and even tunnel-kiln retorts in which the shale is loadedinto small carts and passed through heated tunnels. It will beappreciated by those skilled in the art that such methods entaildisproportionate equipment and operating costs per unit of shalethroughput. Major factors which contribute to such economical operationare poor heat recovery in the retorting system, poor heat utilization,and the need for expensive separation and fractionation equipment toseparate the liquid product into utilizable hydrocarbons.

It has now been discovered that liquid products can be recovered fromhydrocarbonaceous solids by means of a method and apparatus whichpermits eicient heat utilization and which provides a novel means forfractionating the reaction products.

Accordingly, it is an object of this invention to provide a method andapparatus for eliiciently retorting hydrocarbonaceous solids such as oilshale without excessive heat loss. Another object is to provide a methodand apparatus wherein the amount of elort expended in recovery of theretorted products is greatly curtailed. A further object is to provide amethod and apparatus for accomplishing the retorting of shale andsimilar materials with a relatively substantial reduction in the amountand cost of equipment required therefor. Other objects and advantages ofthe present invention will become apparent to those skilled in the artfrom the following detailed description considered in conjunction withthe drawings wherein:

Figure l presents a schematic drawing of the apparatus of the presentinvention;

Fig. 2 presents a more detailed embodiment of the apparatus set forth inFigure 1;

Fig. 3 presents a diagrammatic representation of a fce preferredembodiment of the apparatus and process of this invention; and

Fig. 4 presents a diagrammatic representation of still anotherembodiment of the present invention.

In the drawings, in so far as possible, like parts have been given thesame reference number. Referring now more particularly to Figure l, thebasic apparatus of this invention may be appreciated. In general, theapparatus comprises an elongated cylindrical vessel 2, provided with aseal leg 3, a conical shaped internal cover disposed at the lowerextremity of the seal leg 3 and having a plurality of orifices 10therein. In the upper, or condensing and heat exchange, zone of thereactor proper, there is provided a trap tray 4 disposed around theinner wall of the reactor. The trap tray 4 is provided with a pipe 7 topermit draw-off of liquid products. The design of the trap tray 4provides an annular opening for constricted passage 35. In the lowerregion of reactor 2, there is provided a gas distributing device 23 anda series of baffle plates 26 and 27 having orices 28 and 29. Below thebales there is an air inlet 30 and a drawot' tube 24. In operation, rawcrushed hydroccarbonaceous material, such as oil shale, is carried tothe top of the reactor by means of a suitable lift device 1, e.g., abucket elevator. The crushed shale thus fed into the top of the reactorgravitates downward in a substantially compact mass through the seal leg3 and into the main portion of the reactor. Inert gases such as flue gasare introduced into the feed leg via pipe 9 to provide a seal u whichprevents the escape of gaseous products from the reactor. As the coldshale gravitates through the condensing and heat exchange zone, it iscontacted with the hot condensible and non-condensible vaporous productsof the process. Upon contact with the hot vaporous products, the coldshale is heated and the condensible products are liquefied and gravitatedownwardly through the b ed of shale. Due to'the restricted opening 3S aportion of the bed of shale, immediately above the trap tray 4, becomessubstantially immobile. The .condensed liquid products gradually tricklethrough the zone of immobile shale and eventually reach the trap tray 4.The noncondensible hot gaseous products of the process are passedthrough openings 10 into an annular collecting zone 11. These gases arethen withdrawn via pipe 13 through pump 12. A portion of the hot gasesis sent to a gas recovery plant through pipe 14. The remainder of thehot gases is recycled through pipe 15 into the gas distributing devicev23. By means of this operation, the heat requirements of the shaleretorting are satisfied. The shale gravitating downwardly passes througha combustion zone and thence through the openings 28 and 29 in thebaffles 26 and 27. Below the baes, a combustion-supporting gas, such asair or oxygen, is introduced into pipe 30, pressured by means of pump18. As the combustion-supporting gas passes upwardly through the battledregion, it is heat exchanged with the hot spent shale so that the gasattains a temperature sufficient to support combustion. Thereafter thespent shale is withdrawn through conduit 24. In order to provide a moreeflicient distribution of the raw shale in the upper portion of thereactor, a conically-shaped baille 5 is positioned immediately below theopening of the seal leg 3.

In Fig. 2 there is set forth another embodiment or renement of theprocess described in Figure 1. As has been described hereinbefore, rawcrush shale is introduced into the upper portion of the reactor where itis heat exchanged with the non-condensible and condensible vaporousproducts of the reaction. In the present embodiment, however, the traptray 4 is provided with one or more baiiles 6 which divide the traptrays into 2 or more sections. Each section is provided with a separatedrawot tube 7 and 8. By means of this arrangement, a rough 3.fractionation of the liquid product is achieved in the reactor itself.Accordingly, the amount of fractionation required externally is greatlydiminished.

Another improvement in `the embodiment shown in Fig. 2 relates to theutilization of the recycled gas via pipe 15. The stream of recycle gasis split into two streams, one stream passes `through pipe 22 into gasdistributing device 23. The remainder of the recycle gas passes throughpipe 16, wherein it is mixed with a portion of the combustion-supportinggas supplied via pipe 20. The resulting mixture of combustion-supportinggas and recycle gas is then passed through a gas distributing device 21into the bed of shale. As was described hereinbefore, the remainder ofthe combustion-supporting gas is passed into the lower portion of thereactor via pipe 3 0.V The remaining operations involved in theembodiment `f Fis 2 are Sbsfantiallr the Saale as those de' scribed in`conjunction with the discussion 4of Figure l.

Aps -was mentioned hereinbefore, the oxygen-containing gases absorbedheat from the spent shalev as they passed therethrough. The temperatureof the gaseous mixture is thus raised to the ignition point at which theoxygen contained therein reacts with the combustibles present in thesystem, such as the combustible components of the gaseous mixture andthe coke contained in the spent shale. The combustion thus initiatedgenerates the required amount of heat to maintain the entire process inthermal balance. This is an important feature of the present processwhich serves to minimize heat loss. Since the heat recovery from theincoming and outgoing process is substantially complete, only a smallamount of net combustion heat must be supplied to make up heat loss andheat reaction. The temperature required to achieve combustion isordinarily within the range varying between about 1000 F. and about 1500F. Accordingly, in order to utilize more effectively the heat evolvingfrom the combustion zone, it is preferred to split the recycle gasstream into two or more streams as was illustrated in Fig. 2. Generally,the amount of recycle gas conducted to the retorting zone is betweenabout 1 and about 3 unit weights per unit weight of shale charge. Thetemperature of the gas issuing from the combustion zone is adjusted bymeans of the tlow of residual cold recycle gas lead to the pipe 22 andgas distributor 23. Contact between the residual recycle gas and the gasfrom the combustion zone takes place in the mixing zone of the reactionvessel. The resulting gaseous mixture rises to the retorting zone. Ingeneral, the temperature of the gas entering the retorting zone variesbetween about 800 F. and about 1000 F. The temperatures in excess of theforegoing range are usually to be avoided in the retorting Zone, becauseexcessively high temperatures promote undesired secondary distillationand/or cracking of the shale oil released in the retorting zone. In atypical operation, the volume and temperature of the gas conducted tothe retorting zone varies between about 120 and about 160 pounds of gasper 100 pounds of shale charge at a temperature of about 1000 F.

Suiiicient air or other suitable combustion-supporting gas is suppliedto the bottom of the reacting vessel for the purpose of burningcombustibles and furnishing adequate heat to maintain the process atthermal balance. In addition to the quantity of air thus supplied,sufficient cold recycle gas is introduced in the lower portion of thereaction vessel to dilute the oxygen content of the com bustible gas andto cool the hot spent shale. A secondary stream of cold recycle gas isintroduced into the reaction vessel at a point immediately overlying thecombustion zone. This secondary'stream is contacted with the gaseousproducts of combustion in an amount suicient to adjust the volume andthe temperature of the gaseous mixture conducted to the retorting zone.

During the passage of the crushed shale yfeed downwardly through thereaction vessel, the cold shale becomes heated by contact with thecondensi'ole and non-` condensible products of the process which passupwardly through the condensing and heat exchange zone. The temperatureattained by the shale in this zone is generally in the range of about500 to about 600 F. The temperature of the shale thus preheated whichenters the retorting zone should be above the dew point of the vaporstream leaving the retorting zone. Condensation of the shale oil vaporsis effected upon contact of the rising hot products of retortation withthe downwardlymoving cold shale. This condensation is largely confinedto a separate zone, partly by reason yof the design of this zone whichpermits drainage and withdrawal of the condensate as it is formed, andin part by the relatively high vapor velocity of gaseous productsentering the condensing zone due to the constricted passage 35 in thetrap tray section. This further counteracts any tendency for condensateto run down into the underlying ,retorting zone. The rsmall `amount ofcondensate which may find its way into the lretorting zone isrevaporized therein, and again passed into the upper, condensing zene,wherein it is collected and removed as liquid shale oil.

In practice it may be desirable to recycle at least a portion of theliquid product in order to achieve better fractionation. Such operationis illustrated in Fig. 3 which shows only a portion of the reactor. Aportion of the liquid product in the collecting tray 4 can be withdrawnthrough pipe 4G. Into pipe 41 is introduced a gaseous carrier mediumwhich is commingled with the liquid product in a mixing zone 43. Themixture is then conducted through pipe 44 to a spraying device 45. Theliquid product passes through the orifices 10 into the condensing andheat exchange zone. In this zone the recycled liquid product can befurther vaporized and condensed and eventually pass into the collectingtray 4 with a better degree of fractionation. Preferably, in suchoperation there will be two or more baffles 6 which will serve to dividethe collecting tray 4 into three or more sections.

In order to elect more efficient condensation of the liquid products,cooling may be supplied to a portion of the bed immediately above thecollecting tray 4. Such an embodiment is illustrated in Fig. 4. Coolingcoils 31 are disposed in the interior of the reaction vessel 2,positioned immediately above the trap trays 4. A cooling mediumcirculated through coils 31 serves to lower thc temperature of the shaleand gaseous products immediately above the trap trays. In this mannerthere is effected a greater degree of condensation of condensiblevaporous products in this section. Accordingly, it is a preferred aspectof the present invention to subject the vaporous products in thecondensing and heat exchange zone to'cooling for the purpose ofpromoting condensation thereof.

As will be appreciated by those skilled in the art, the process andapparatus of this invention provides an eicient means for educting oilfrom hydrocarbonaceous fluids. By means of the method of this invention,substantially complete heat recovery is accomplished in the reactionvessel without the necessity for heat exchange from an external source,thereby eliminating excessive heat loss which has been encounteredheretofore. All products of the instant process including the spentshale are withdrawn at substantially atmospheric temperatures. Theinternal fractionation of the total retorted products serves to greatlyreduce the product recovery facilities ordinarily required in retortingprocess.

A construction of the apparatus of this invention affords numerousadvantages. The crushed shale and gaseous products are passedthrough agone of restricted crosssection wherein heat exchange takes place. Dueto the restricted cross-section, the rate of upward gaseous fiowprevents, substantially, the downward ow of condensed liquid productinto the retorting zone. The high vapor velocities restricted to therestricted cross-sectional area zone offers advantages of constructionand of operation.

lSince high vapor velocities are not used throughout the reactor,adequate time for combustion and retorting is achieved without thenecessity of making the apparatus unduly large, particularly in height.Likewise, erosion of the equipment and shale is minimized by thesubstantial elimination of high vapor velocities in the leg section.

The operation described herein had been directed particularly to theretorting of oil shale. It is to be strictly understood, however, thatthe process and apparatus of this invention are likewise applicable foreffecting retortation of other oil-containing or oil-producing solids,such as coal, peat, lignite, tar sands and the like.

Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resorted to, without departing from the spirit andscope of this invention, as those skilled in the art will readilyunderstand. Such variations and modifications are considered to bewithin the purview and scope of the appended claims.

I claim:

1. In a method for producing shale oil from oil shale by heating adownwardly moving compact bed of cold, crushed oil shale and liowing thehot vaparous products so obtained upwardly through said downwardlymoving bed, whereby condensation of released shale oil vapors isobtained upon contact with the counter-owing cold shale, the improvementwhich comprises internally collecting within said bed at least twoseparate fractions of liquid shale oil condensate of varying boilingpoints and thereafter withdrawing separate streams of each of saidcollected liquid shale oil fractions from contact with said bed.

2. In a method for producing shale oil from oil shale by heating adownwardly moving compact bed of cold,

lying said bed, condensable gas to said bed below the zone o fretortation therein, whereby hot spent shale descending from said zoneis cooled and removing a stream of cold, spent shale from the bottom ofsaid bed.

3. A process for the recovery of shale oil from oil shale, whichcomprises heating crushed oil shade to ignition ternperature, contactinga bed of the resulting hot shale with a stream of air to effectcombustion of combustible matter present therein, owng hot vaporousproducts emitted from the heated shale through a constricted zone ofhigh adjacent said restricted zone, withdrawing separate streams of eachof said collected shale oil fractions, removing noncondensable gas atsubstantially atmospheric temperature overlying the bed of crushed oilshale, recycling a stream of said non-condensable gas to said bed belowthe zone of retortation therein, whereby hot spent shale descending fromsaid zone of retortation is cooled and removing a stream of spent shale,at substantially atmospheric temperature from the bottom of said bed.

4. A process for the recovery of shale oil from oil shale, whichcomprises initiating a zone of combustion in the lower portion of anelongated bed of oil shale, flowing the hot vaporous products upwardlythrough said downwardly moving bed of oil shale, whereby shale oilvapors contained in said vaporous products undergo condensation uponcontact with the counter-owing cold, crushed shale,

collecting within said bed of shale, a plurality of fractions of saidcondensed liquid shale oil having varying boiling points, withdrawing astream of non-condensable gas overlying said bed, recycling a portion ofsaid withdrawn gas to the lower portion of said elongated bed in anamount sucient to adjust the volume and temperature of the gas risingfrom the zone wherein shale is undergoing the aforementioned combustion,causing the aforementioned gaseous products of retortation to owupwardly through said downwardly moving bed, withdrawing separatestreams of said collected liquid shale oil fractions from contact withsaid bed, and removing spent shale substantially freed of combustiblematter from the bottom of said bed.

5. A process for the recovery of shale oil from oil shale, whichcomprises heating crushed oil shale to ignition temperature, contactinga downllowing bed of resulting hot shale with a stream of air to electcombustion of combustible matter present therein, llowing hot vaporousproducts emitted from the heated shale upwardly through a constrictedzone of high vapor velocity, internally cooling the downliowing shale ata point upward and outward of said constricted zone, condensing thevaporous products of retortation which pass upward and outward of saidconstricted zone upon contact with counter-owng cold shale, collecting aplurality of fractions of condensed liquid shale oil of varying boilingpoints within said bed of shale and non-condensable gas overlying thebed of crushed oil shale, recycling astream of said cold,non-condensable gas to the lower portion of .said bed, whereby hot spentshale is the bottom of said bed.

6. In a retorting apparatus for producing shale oil surface of saidreaction vessel at varying distances from the center thereof forcollection of a plurality of fractions of liquid shale oil condensate ofdiffering boiling points, a series of outlet conduits, one of saidconduits extending from each of said trays for effecting separatewithdrawal therefrom of the collected fractions of liquid shale oilcondensate, an outlet for removing non-con densable gas from the top ofsaid reaction vessel, a conduit for recycling said non-condensable gasto the lower interior of said reaction vessel wherein it contactsdownowing hot spent shale, thereby cooling the same, and a conduit inthe bottom of said reaction vessel for electing removal of cold spentshale.

8. In a retorting apparatus for producing shale oil from oil shale, thecombination of an elongated vertical reaction vessel, means forintroducing crushed oil shale to the interior of said reaction vessel,means for heating said crushed oil shale, means, within said reactionvessel, for collecting a plurality of fractions of liquid shale oilcondensate of diiering boiling points, means for cooling heated oilshale and vaporous products released therefrom immediately above theaforesaid collecting means, means for removing non-condensable gas fromsaid reaction ves-- sel, means for cooling spent shale within saidreaction vessel, means for withdrawing cooled spent shale, and means forseparately withdrawing Vfrom the interior of said reaction vessel eachofthe aforesaid condensed liquid shale oil fractions.

9. In a retorting apparatus for producing shale oil from oil shale, thecombination of an elongated vertical reaction vessel, an inlet conduitfor introducing crushed oil shale to the interior of said reactionvessel, means for initiating combustion of said crushed oil shale, aseries of trays aixed to the interior of said reaction vessel forcollecting a plurality of fractions of liquid shale oil condensate ofdiffering boiling points, a series of outlet conduits, one of saidconduits extending from each of said -trays for electing separatewithdrawal therefrom of the collected fractions of liquid shale oilcondensate, an outlet near the top of said reaction vessel for removingnoncondensable gas, conduit for recycling said non-condensable gas tothe lower interior of said reaction vessel wherein it cools downowinghot spent shale and an outlet conduit in the bottom of said reactionvessel for removing cold spent shale.

10. In a retorting apparatus for producing shale oil from oil shale, thecombination of an elongated vertical reaction vessel, means for heatingsaid crushed oil shale to retorting temperature, a series of contiguoustrays positioned along the interior surface of said reaction vessel atvarying distances from the center thereof for collecting a plurality offractions of liquid shale oil condensate of ditfering boiling points, aseries of cooling coils immediately overlying said trays, a series ofoutlet conduits, true of said outlet conduits extending from each ofsaid trays a point outside ysaid reaction vessel for effecting separatewithdrawal therefrom of the collected fractions of liquid shale oilcondensate, an outlet for removing noncondensable gas from the top ofsaid reaction vessel, a conduit for recycling said non-condensable gasto the lower interior of said reaction vessel wherein it contacts andcools dewnowing hot spent shale and an outlet conduit in the bottom ofsaid reaction vessel yfor effecting removal of cold, spent shale.

References Cited in the le of this patent UNITED STATES PATENTS1,781,934v Synder Nov. 18, 1930 2,637,683 Kassel May 5, 1953 2,640,019Berg May 26, 1953 2,707,163 Thibaut Apr. 26, 1955 2,723,225 Elliott Nov.8, 1955 OTHER REFERENCES UNITED STATES PATENT OFFICE CERTIFICATE OECORRECTION May 59 Patent No., 2,885 ,1338

Louis P. Evahs` It is hereb3T certified that error appears n the printedspecification of the above numbered patent requiring correction and thatthe Said Letters Patent should read as corrected below.

nhydroooarbohacefous read m hydro lines 22 and. 23j for vaparousY readwvaporous en;

column 5, line' 23, for

d Shale ne.

Column 2,

oarbonaoeous 1f-1; line 5C, for "Shade rea Signe (SEAL) Attest: KARL H@MNE ROBERT O. WATSON Commissioner of Patents Attesting Oicer

2. IN A METHOD FOR PRODUCING SHALE OIL FROM OIL SHALE BY HEATING ADOWNWARDLY MOVING COMPACT BED OF COLD, CRUSHED OIL SHALE AND FLOWING THEHOT VAPOROUS PRODUCTS SO OBTAINED UPWARDLY THROUGH SAID DOWNWARDLYMOVING BED, WHEREBY SAID OIL SHALE UNDERGOES RETORTATION AND THERELEASED SHALE OIL VAPORS UNDERGO CONDENSATION UPON CONTACT WITH THECOUNTER-FLOWING COLD SHALE, THE IMPROVEMENT WHICH COMPRISES COLLECTING APLURALITY OF LIQUID SHALE OIL FRACTIONS OF DIFFERING BOILING POINTSWITHIN SAID MOVING BED, WITHDRAWING SEPARATE STREAMS OF EACH OF SAIDCOL-